DYNAMIC REFLECTION HIGH-ENERGY ELECTRON-DIFFRACTION OBSERVATION OF 3C-SIC(001) SURFACE RECONSTRUCTION UNDER SI2H6 BEAM IRRADIATION

The transition of 3C-SiC(001) surface superstructures under Si2H6 gas molecular beam irradiation was dynamically observed by reflection high-energy electron diffraction. Starting from the C-terminated c(2 X 2) structure, the surface structure changed in the order of c(2 x 2) --> (2 x 1) --> (5 X 2) --> (3 X 2) with continuing irradiation. The amounts of Si2H6 dose required for the transitions c(2 X 2) --> (5 X 2) and c(2 X 2) --> (3 X 2) were approximately 1.16 and 1.36 times as much as that for c(2 X 2) --> (2 X 1). These ratios are interpreted as the relative amount of the constituent Si atoms of the superstructures. This experimental result supports the simple dimer model for (2 X 1) (1 monolayer of Si) and the additional dimer model for (5 X 2) (1.2 monolayer) and (3 X 2) (1.33 monolayer), respectively, as the proper configurations of these surface superstructures.